tag instead of Entry Title

Hi,

hope someone will help.
I see a flaw in the NIKKON theme which I can’t seem te resolve.
I did a SEO check on the website and it shows up that there aren’t any <h1> tags. I went for a search and indeed there aren’t any (if not manually inserted in the page) because of hierargie reasons it’s important to let it come up in the top of the page.
The entry-title would be the best for it. When I look in the page source it has a <h3> tag! (In my case: <h3 class=”entry-title”>Miniatuur schilderijen</h3>)
I searched all files in Nikkon to try change this. What I found (content-search.php and content.php)I made the changes to the <h3> tag on the entry-title and made changes to it in the child theme.
Only other file I found it was content-single.php where the tag was okay.
After making these small changes nothing happened! I keep getting a >h3> tag where I want the <h1> tag.
I really need to change this because if this can’t be done in the php I have to change all my pages, and that is a lot of work instead of changing a single line of code….